CN117048426A - Electric quantity balancing method and system for vehicle battery pack and vehicle - Google Patents
Electric quantity balancing method and system for vehicle battery pack and vehicle Download PDFInfo
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- CN117048426A CN117048426A CN202311088276.5A CN202311088276A CN117048426A CN 117048426 A CN117048426 A CN 117048426A CN 202311088276 A CN202311088276 A CN 202311088276A CN 117048426 A CN117048426 A CN 117048426A
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- 238000000034 method Methods 0.000 title claims abstract description 75
- 230000005611 electricity Effects 0.000 claims abstract description 57
- 239000013589 supplement Substances 0.000 claims abstract description 31
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 51
- 238000007600 charging Methods 0.000 claims description 50
- 238000004364 calculation method Methods 0.000 claims description 24
- 230000003068 static effect Effects 0.000 claims description 12
- 238000012545 processing Methods 0.000 claims description 11
- 238000010277 constant-current charging Methods 0.000 claims description 9
- 230000009467 reduction Effects 0.000 claims description 6
- XOFYZVNMUHMLCC-ZPOLXVRWSA-N prednisone Chemical compound O=C1C=C[C@]2(C)[C@H]3C(=O)C[C@](C)([C@@](CC4)(O)C(=O)CO)[C@@H]4[C@@H]3CCC2=C1 XOFYZVNMUHMLCC-ZPOLXVRWSA-N 0.000 claims description 5
- 230000001502 supplementing effect Effects 0.000 description 25
- 238000004891 communication Methods 0.000 description 9
- 238000005265 energy consumption Methods 0.000 description 9
- 238000007599 discharging Methods 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- 238000012216 screening Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 7
- 230000006870 function Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 238000004590 computer program Methods 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
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- 238000003491 array Methods 0.000 description 2
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- 239000003792 electrolyte Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 1
- 229910052493 LiFePO4 Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
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- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
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- 230000006872 improvement Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 239000010450 olivine Substances 0.000 description 1
- 229910052609 olivine Inorganic materials 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
- B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
- B60L58/12—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to state of charge [SoC]
- B60L58/13—Maintaining the SoC within a determined range
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
- B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
- B60L3/0046—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to electric energy storage systems, e.g. batteries or capacitors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Secondary Cells (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The application discloses a method and a system for balancing electric quantity of a vehicle battery pack and a vehicle, wherein the method comprises the following steps: if the vehicle is in a power-on state and the vehicle meets an equalization condition for triggering equalization, acquiring battery data of a vehicle battery pack; calculating to obtain equalization time and equalization required electric quantity according to the battery data, and selecting an equalization mode according to a use scene and a use habit; and obtaining the low-voltage core number, if the low-voltage core number is smaller than or equal to the preset core number, selecting a storage battery with preset voltage to supplement electricity for the low-voltage core until the balance reaches the target electric quantity, and if the low-voltage core number is larger than the preset core number, reducing the electric quantity of the high-electric-quantity core to the target electric quantity by adopting a resistance power consumption mode. According to the application, the equalization condition for triggering the equalization of the battery is increased, the equalization mode is intelligently selected, the equalization time is accurately calculated, the occurrence of error equalization is avoided, the power-up equalization or the discharge equalization is selected according to the situation, and the performance and the service life of the vehicle battery pack are improved.
Description
Technical Field
The application relates to the technical field of vehicle power battery management equalization, in particular to an electric quantity equalization method and system of a vehicle battery pack, a vehicle and a computer readable storage medium.
Background
The lithium iron phosphate battery (Lithium iron phosphate Battery) is a lithium ion battery which uses lithium iron phosphate (LiFePO 4) as a positive electrode material and carbon as a negative electrode material, wherein the rated voltage of a single battery is 3.2V, and the charging cut-off voltage is 3.6V-3.65V. During the charging process, part of lithium ions in the lithium iron phosphate are separated out and transferred to the negative electrode through electrolyte, and are intercalated into a negative electrode carbon material; and simultaneously, electrons are released from the positive electrode and reach the negative electrode from an external circuit, so that the balance of chemical reaction is maintained. In the discharging process, lithium ions are separated from the negative electrode and reach the positive electrode through the electrolyte, meanwhile, electrons are released from the negative electrode, and reach the positive electrode from an external circuit to provide energy for the outside.
The lithium iron phosphate material consists of LiFePO4 with an olivine structure, and the lithium iron phosphate battery has the advantages of long cycle life, low heat productivity, good thermal stability, low cost and the like. Due To the price advantage, and along with the mature and application of the technology of integrating the battery Cell into a battery PACK (CTP, cell To PACK), the energy density of a lithium iron phosphate battery system is improved, so that the demand of the lithium iron phosphate battery in the power battery market is continuously increased, and the lithium iron phosphate battery is widely applied To the plug-in hybrid electric vehicle.
The disadvantages of lithium iron phosphate batteries are also evident: (1) poor power performance at low temperatures; (2) The lithium iron phosphate is stable in platform voltage in the charging and discharging process, basically does not change, and the error Of calculating the SOC (State Of Charge, used for reflecting the residual capacity Of the battery) is larger by an open-circuit voltage and ampere-hour integration method (the capacity Of the battery is calculated by integrating the current and time in the discharging process Of the battery). There are many reasons for the inconsistency of the batteries, for example, the inconsistency of the self-discharge rate of different single batteries, the inconsistency of the environmental conditions such as the use temperature, etc., the variability of the manufacturing process when the batteries leave the factory, etc. In addition, due to continuous changes of temperature, polarization and service cycle, the deviation of SOC estimation is larger than that of other materials, and pressure differences are easily generated among different battery cells in the battery pack, so that the uniformity differences among the cells in the battery pack are caused. The lithium iron phosphate battery used for the plug-in hybrid electric vehicle and the pure electric vehicle is complex in service environment and working condition, unavoidable performance and voltage inconsistency problems of single battery cells can occur in the use process, the battery pack single battery cells are inconsistent, the whole battery pack performance can be affected, and the service life of the battery pack is reduced.
Therefore, an equalization system is needed to solve the problem of single-cell voltage difference in the battery pack. The voltage characteristic of the lithium iron phosphate has less balancing opportunities, so that the balancing time is difficult to calculate accurately, the error balancing condition is more, the service life and performance of the lithium iron phosphate battery pack are reduced, and even the battery pack is damaged or potential safety hazards are generated when the service life and performance of the lithium iron phosphate battery pack are serious.
Accordingly, the prior art is still in need of improvement and development.
Disclosure of Invention
The application mainly aims to provide an electric quantity balancing method and system for a vehicle battery pack, a vehicle and a computer readable storage medium, and aims to solve the problems that in the prior art, because of the voltage characteristic of the vehicle battery pack (lithium iron phosphate), the balancing opportunity is low, the balancing time is difficult to calculate accurately, the number of wrong balancing situations is high, the passive balancing time is long, the service life and performance of the vehicle battery pack (lithium iron phosphate battery pack) are reduced, and even the vehicle battery pack is damaged or potential safety hazards are generated in serious cases.
An embodiment of a first aspect of the present application provides a method for equalizing electric power of a vehicle battery pack, including the steps of: if the vehicle is in a power-on state and the vehicle meets an equalization condition for triggering equalization, acquiring battery data of a vehicle battery pack; calculating to obtain equalization time and equalization required electric quantity according to the battery data, and selecting an equalization mode according to a use scene and a use habit; and obtaining the low-voltage core number, if the low-voltage core number is smaller than or equal to the preset core number, selecting a storage battery with preset voltage to supplement electricity for the low-voltage core until the balance reaches the target electric quantity, and if the low-voltage core number is larger than the preset core number, reducing the electric quantity of the high-electric-quantity core to the target electric quantity by adopting a resistance power consumption mode.
According to the technical means, when the vehicle is detected to meet one of a plurality of equalization conditions, the embodiment of the application can acquire the related battery data of the vehicle battery pack, so that the equalization time and the equalization required electric quantity are calculated, then the equalization mode is intelligently selected according to different use scenes and use habits of users, the equalization time is calculated as accurately as possible, the occurrence of error equalization is avoided, finally the electricity compensation equalization or the discharge equalization is selected according to the comparison condition of the number of low-voltage electric cores and the number of preset electric cores, the electricity compensation equalization is performed on the low-voltage electric cores by selecting the storage battery with the preset voltage until the equalization reaches the target electric quantity, the equalization load is reduced, the equalization efficiency is improved, the resistance energy consumption equalization system load is reduced, the electric quantity of the high-electric-quantity electric core is reduced to the target electric quantity by adopting the resistance electricity consumption mode, the electricity consumption is performed on the high-electric-quantity electric core, and the equalization current is small.
Optionally, in one embodiment of the present application, the equalization condition includes: the lowest SOC of the battery cell is larger than the first percentage, the difference between the highest SOC and the lowest SOC of the battery cell is larger than the second percentage, the maximum voltage difference of the battery cell is larger than a preset voltage value, the residual balancing time is larger than 0, the whole vehicle has no faults, the temperature of a balancing circuit is smaller than the first temperature and the temperature of the battery cell is smaller than the second temperature, and the electric quantity of a storage battery during power compensation balancing is larger than the third percentage SOC; and when any one of the equalization conditions is met, the vehicle is indicated to meet the equalization condition for triggering equalization.
According to the technical means, the embodiment of the application can set a plurality of equalization conditions, and through the multipoint equalization triggering conditions, the equalization opportunity is increased, the equalization conditions relate to the lowest SOC of a battery cell, the difference between the highest SOC and the lowest SOC of the battery cell, the maximum pressure difference of the battery cell, the residual equalization time, the whole vehicle has no faults, the equalization circuit temperature, the battery cell temperature and the battery electric quantity during the power supply equalization, and the equalization conditions indicate that the vehicle meets the equalization conditions for triggering the equalization when any one of the equalization conditions is met, and the conditions for triggering the equalization of the battery are increased, so that the equalization opportunity of the battery pack of the vehicle is increased.
Optionally, in one embodiment of the application, the battery data includes a battery voltage, a battery charge, and a battery current.
According to the technical means, the embodiment of the application can collect the battery voltage, the battery electric quantity and the battery current of the battery pack of the vehicle after the vehicle is in the power-on state and the vehicle meets the equalization condition for triggering equalization, so that the equalization time and the equalization required electric quantity can be accurately calculated according to the battery voltage, the battery electric quantity and the battery current conveniently.
Optionally, in one embodiment of the present application, the equalizing time includes: the equalization time of passive resistor and the equalization time of battery power supply; passive resistance equalization time = Δe/(I) 2 * R), wherein delta E is balanced electric quantity, I is balanced current, and R is balanced resistor; battery charge equalization time = Δe/(p×η), where Δe is the equalization power, P is the battery equalization power, and η is the loss factor.
According to the technical means, the equalization time in the embodiment of the application comprises the passive resistance equalization time and the battery power-on equalization time, wherein the passive resistance equalization is equalization through resistance power consumption, the battery power-on equalization is equalization through battery power-on equalization, the passive resistance equalization time is calculated according to the equalization electric quantity, the equalization current and the equalization resistance, the battery power-on equalization time is calculated according to the equalization electric quantity, the battery equalization power and the loss factor, and the calculated corresponding equalization time is convenient to use in discharge equalization or power-on equalization later.
Optionally, in one embodiment of the present application, the calculating the equalization required power according to the battery data specifically includes: acquiring a cell voltage difference, and judging whether the cell voltage difference is larger than a voltage difference threshold value or not; if the voltage difference of the battery cell is larger than the voltage difference threshold, judging whether the standing time of the whole vehicle is longer than the preset time and judging whether the SOC interval is in the preset range SOC interval; if the standing time of the whole vehicle is longer than the preset time and the SOC interval is in the preset range SOC interval, selecting an OCV-SOC table lookup method to calculate the electric quantity required by equalization; if the standing time of the whole vehicle is not longer than the preset time or the SOC interval is not in the preset range SOC interval, judging whether the vehicle is in a direct current charging state or not; if the vehicle is in a direct current charging state, calculating the electric quantity required by equalization through a dQ/dV-SOC curve of constant current charging of a vehicle battery pack; if the vehicle is not in the direct-current charging state, judging whether the vehicle is in the alternating-current charging state; if the vehicle is in an alternating current charging state, the battery cells are screened at the charging end, and the electric quantity required by equalization is calculated and is larger than the fourth percentage of SOC.
According to the technical means, the method for calculating the electric quantity required by equalization can be selected according to the judgment of the voltage difference of the battery cell, the standing time of the whole vehicle, the SOC interval, the direct current and alternating current charging states, and comprises three ways for calculating the electric quantity required by equalization, namely an OCV-SOC table look-up method, a constant-current charging dQ/dV-SOC curve of a vehicle battery pack and calculation of the charging end, so that the electric quantity required by equalization can be accurately calculated, and the calculated electric quantity required by equalization can be conveniently used in the subsequent discharging equalization or the electricity supplementing equalization.
Optionally, in one embodiment of the present application, the selecting an equalization method according to a usage scenario and usage habits specifically includes: judging whether the whole vehicle is electrified; if the whole vehicle is not electrified, adopting off-line equalization during parking; if the whole vehicle is electrified, judging whether the vehicle speed is 0; if the vehicle speed is 0, adopting static balancing; if the vehicle speed is not 0, driving equalization is adopted.
According to the technical means, the balancing mode can be intelligently selected according to the use scene and the use habit of the user, and the balancing modes comprise off-line parking balancing, standing balancing and driving balancing, so that the most suitable balancing mode can be selected according to different conditions, and the balancing safety of the vehicle battery pack is improved.
Optionally, in an embodiment of the present application, the obtaining the low voltage core count, if the low voltage core count is less than or equal to a preset core count, selecting a storage battery with a preset voltage to supplement power to the low voltage core until balance reaches a target power, and if the low voltage core count is greater than the preset core count, reducing the power of the high power core to the target power by adopting a resistive power consumption mode, including: obtaining the number of low-voltage cores, and judging whether the number of the low-voltage cores is smaller than or equal to the total number of the A-type electric cores, wherein A is a constant smaller than 0.5; if the number of the low-voltage cores is smaller than or equal to the total number of the electric cores A, a storage battery with preset voltage is selected to supplement electricity to the low-voltage cores through a high-low voltage direct current converter until the balance reaches the target electric quantity; and if the low-voltage core number is larger than the total number of the battery cores A, reducing the electric quantity of the battery core with high electric quantity to the target electric quantity by adopting a resistance power consumption mode.
According to the technical means, the embodiment of the application can select power-supplementing equalization or discharging equalization according to the comparison condition of the number of the low-voltage electric cores and the number of the preset electric cores, if the number of the low-voltage electric cores is smaller than or equal to the total number of the electric cores A, the power-supplementing equalization is selected, namely, a storage battery with preset voltage is selected to supplement power to the low-voltage electric cores through a high-low-voltage direct-current converter until the equalization reaches the target electric quantity, the equalization load is reduced, the equalization efficiency is improved, the load of a resistance energy consumption equalization system is reduced, if the number of the low-voltage electric cores is larger than the total number of the electric cores A, the discharging equalization is selected, namely, the electric quantity of the high-electric-quantity electric cores is reduced to the target electric quantity by adopting a resistance power consumption mode, the power consumption is carried out on the high-electric-quantity electric cores, and the equalization current is small.
Optionally, in one embodiment of the present application, the method for balancing the electric quantity of the vehicle battery pack further includes: when the battery cell is charged through the storage battery with preset voltage, if the electric quantity of the storage battery is lower than the fifth percentage SOC, the storage battery is out of balance, the vehicle battery pack supplements the electric quantity of the storage battery, if the balance condition is met, the storage battery is controlled to supplement the electric quantity in balance, and if the electric quantity of the storage battery reaches the target electric quantity or the electric quantity of the storage battery is not met, the electric quantity of the storage battery is stopped.
According to the technical means, the embodiment of the application can control the vehicle to carry out reverse power supply when the electric quantity of the storage battery is lower than a certain SOC, namely, the storage battery is supplied with power through the vehicle battery pack, after the power supply of the storage battery is completed, if the balance condition is met, the balanced power supply is continued, or the power supply cannot be carried out or stopped when the power supply reaches the target electric quantity, so that the balanced operation of the vehicle battery pack cannot be realized when the electric quantity of the storage battery is too low.
Optionally, in an embodiment of the present application, the obtaining the low voltage core count, if the low voltage core count is less than or equal to a preset core count, selecting a storage battery with a preset voltage to supplement power to the low voltage core until the balance reaches a target power, and if the low voltage core count is greater than the preset core count, reducing the power of the high power core to the target power by adopting a resistive power consumption mode, and then further including: judging whether the equalization time is more than 0; if the equalization time is greater than 0, preserving the equalization time in real time, and performing reduction processing on the equalization time; judging whether a fault or a limiting condition affecting balance exists or not; if no fault or limiting condition affecting balance exists, judging whether a power-down request is detected; and if the power-down request is detected, storing the balance residual duration and the balance parameters, and powering down.
According to the technical means, the embodiment of the application can judge whether the balancing time is greater than 0 after the balancing is performed according to the vehicle state, the selected balancing mode and the calculated balancing time, compare the last unfinished balancing and selecting the optimal balancing strategy, store the balancing time in real time if the balancing time is greater than 0, perform the number reduction processing on the balancing time, namely perform balancing condition judgment after balancing for a certain time, subtract the balanced time from the balanced time to obtain the residual balancing time, then judge whether a fault or a limiting condition affecting the balancing exists, finally judge whether a power-down request is detected or not if the fault or the limiting condition affecting the balancing does not exist, and store the balanced residual time and the balancing parameter and power down if the power-down request is detected, so that the electric quantity balancing operation of the vehicle battery pack is more comprehensive and the safety is higher.
Optionally, in one embodiment of the present application, the method for balancing the electric quantity of the vehicle battery pack further includes: if the vehicle is not in the power-on state, judging whether the BMS system meets the timed wake-up or the offline equalization condition; if the BMS system meets the timing wake-up or offline equalization conditions, reading historical residual equalization time and equalization modes; judging whether the historical residual equalization time is larger than an offline equalization time threshold; if the historical residual balancing time is greater than the offline balancing time threshold, setting the offline balancing time as the offline balancing time threshold, and performing offline balancing; the BMS wake-up time is set to: off-line equalization time threshold + preset time.
According to the technical means, when the vehicle is not electrified, the embodiment of the application can further judge whether the BMS system is awakened at regular time or whether an offline balancing condition is met, namely, the vehicle is stopped for a long time and is not started, the BMS system is awakened at a certain time interval by the whole vehicle, if the BMS system is awakened at regular time or meets the offline balancing condition, the historical residual balancing time and the balancing mode are read, then whether the historical residual balancing time is larger than an offline balancing time threshold value is judged, if the historical residual balancing time is larger than the offline balancing time threshold value, the offline balancing time is set as the offline balancing time threshold value, and then the offline balancing is carried out, and the BMS awakening time is set as: the offline equalization time threshold value is + the preset time, so that the situation that the electric quantity equalization operation of the vehicle battery pack is not performed when the vehicle is not electrified can be avoided.
Optionally, in one embodiment of the present application, the determining whether the historical remaining equalization time is greater than an offline equalization time threshold further includes: if the historical remaining equalization time is not greater than the offline equalization time threshold, the BMS wakeup time is directly set to: off-line equalization time threshold + preset time.
According to the technical means, when the historical residual balancing time is not greater than the offline balancing time threshold, the BMS wake-up time can be directly set as: and the off-line equalization time threshold value is plus the preset time, so that the electric quantity equalization operation of the vehicle battery pack is more comprehensive and intelligent.
Optionally, in one embodiment of the present application, the vehicle battery pack includes: and (5) a lithium iron phosphate battery pack.
According to the technical means, the embodiment of the application can be mainly used for the electric quantity balancing method of the lithium iron phosphate battery pack, because the lithium iron phosphate battery pack is the battery pack which is the most representative of the vehicle battery pack, namely the multi-point triggering high-efficiency intelligent balancing method is mainly used for the lithium iron phosphate battery pack, but is not limited to the lithium iron phosphate battery pack.
An embodiment of the second aspect of the present application provides a power equalization system for a vehicle battery pack, the power equalization system for a vehicle battery pack including: the data acquisition module is used for acquiring battery data of a vehicle battery pack if the vehicle is in a power-on state and the vehicle meets an equalization condition for triggering equalization; the equalization calculation module is used for calculating equalization time and equalization required electric quantity according to the battery data, and selecting an equalization mode according to a use scene and a use habit; the balance control module is used for obtaining the low-voltage core number, if the low-voltage core number is smaller than or equal to the preset core number, the storage battery with preset voltage is selected to supplement electricity for the low-voltage core until the balance reaches the target electric quantity, and if the low-voltage core number is larger than the preset core number, the electric quantity of the high-electric-quantity electric core is reduced to the target electric quantity in a resistance power consumption mode.
Optionally, in one embodiment of the present application, the equalization condition includes: the lowest SOC of the battery cell is larger than the first percentage, the difference between the highest SOC and the lowest SOC of the battery cell is larger than the second percentage, the maximum voltage difference of the battery cell is larger than a preset voltage value, the residual balancing time is larger than 0, the whole vehicle has no faults, the temperature of a balancing circuit is smaller than the first temperature and the temperature of the battery cell is smaller than the second temperature, and the electric quantity of a storage battery during power compensation balancing is larger than the third percentage SOC; and when any one of the equalization conditions is met, the vehicle is indicated to meet the equalization condition for triggering equalization.
Optionally, in one embodiment of the application, the battery data includes a battery voltage, a battery charge, and a battery current.
Optionally, in one embodiment of the present application, the equalizing time includes: the equalization time of passive resistor and the equalization time of battery power supply; passive resistance equalization time = Δe/(I) 2 * R), wherein delta E is balanced electric quantity, I is balanced current, and R is balanced resistor; battery charge equalization time = Δe/(p×η), where Δe is the equalization power, P is the battery equalization power, and η is the loss factor.
Optionally, in one embodiment of the present application, the equalization calculation module includes: the cell differential pressure acquisition and comparison unit is used for acquiring the cell differential pressure and judging whether the cell differential pressure is larger than a differential pressure threshold value or not; the static time length and SOC interval judging unit is used for judging whether the static time length of the whole vehicle is longer than a preset time and judging whether the SOC interval is in a preset range SOC interval or not if the voltage difference of the battery cell is greater than the voltage difference threshold value; the first equalization required electric quantity calculation unit is used for selecting an OCV-SOC table look-up method to calculate equalization required electric quantity if the whole vehicle is longer than the preset time and the SOC interval is in the preset range SOC interval when standing; the direct-current charging state judging unit is used for judging whether the vehicle is in a direct-current charging state or not if the standing time of the whole vehicle is not longer than the preset time or the SOC interval is not in the preset range SOC interval; the second equalization required electric quantity calculation unit is used for calculating the equalization required electric quantity through a vehicle battery pack constant-current charging dQ/dV-SOC curve if the vehicle is in a direct-current charging state; an ac charge state judgment unit configured to judge whether the vehicle is in an ac charge state if the vehicle is not in a dc charge state; and the third equalization required electric quantity calculation unit is used for screening the battery cells at the charging end if the vehicle is in an alternating-current charging state, and calculating the equalization required electric quantity larger than the fourth percentage SOC.
Optionally, in one embodiment of the present application, the equalization calculation module further includes: the first whole vehicle power-on judging unit is used for judging whether the whole vehicle is powered on or not; the first equalization mode selection unit is used for adopting off-line equalization when the whole vehicle is not electrified; the vehicle speed judging unit is used for judging whether the vehicle speed is 0 or not if the whole vehicle is electrified; a second equalization mode selecting unit for adopting static equalization if the vehicle speed is 0; and the third equalization mode selecting unit is used for adopting driving equalization if the vehicle speed is not 0.
Optionally, in one embodiment of the present application, the equalization control module includes: the low-voltage core number acquisition comparison unit is used for acquiring the low-voltage core number and judging whether the low-voltage core number is smaller than or equal to the total number of the electric cores A, wherein A is a constant smaller than 0.5; the power-supplementing balancing unit is used for selecting a storage battery with preset voltage to supplement power to the low-voltage electric core through the high-low voltage direct current converter if the number of the low-voltage electric cores is smaller than or equal to the total number of the electric cores A until balancing reaches the target electric quantity; and the discharging equalization unit is used for reducing the electric quantity of the high-electric-quantity electric core to the target electric quantity by adopting a resistance power consumption mode if the low-voltage electric core number is larger than the total number of the electric cores A.
Optionally, in an embodiment of the present application, the system of the embodiment of the present application further includes: and the reverse electricity supplementing unit is used for when the battery cell is supplemented with electricity through the storage battery with preset voltage, if the electric quantity of the storage battery is lower than the fifth percentage SOC, the storage battery is out of balance, the vehicle battery pack supplements the electric quantity of the storage battery, and if the balance condition is met, the storage battery is controlled to supplement the electric quantity in balance, and if the electricity supplementing reaches the target electric quantity or the electricity supplementing condition is not met, the electricity supplementing is stopped. An equalization time judging unit for judging whether the equalization time is greater than 0; the equalization time processing unit is used for storing the equalization time in real time and performing reduction processing on the equalization time if the equalization time is greater than 0; a fault or constraint condition judging unit for judging whether a fault or constraint condition affecting balance exists; a power-down request judging unit for judging whether a power-down request is detected if there is no fault or limiting condition affecting equalization; and the power-down storage unit is used for storing the balance residual duration and the balance parameters and powering down the battery if the power-down request is detected. The BMS system judging unit is used for judging whether the BMS system meets the timed wake-up or the offline balance condition if the vehicle is not in the power-on state; the balancing time and balancing mode reading unit is used for reading historical residual balancing time and balancing mode if the BMS system meets the timing wake-up or offline balancing condition; the historical residual equalization time judging unit is used for judging whether the historical residual equalization time is larger than an offline equalization time threshold; the off-line balancing unit is used for setting the off-line balancing time as the off-line balancing time threshold value and then carrying out off-line balancing if the historical remaining balancing time is larger than the off-line balancing time threshold value; the first wake-up time setting unit is configured to set a BMS wake-up time to: off-line equalization time threshold + preset time. The second wake-up time setting unit is configured to directly set the BMS wake-up time to be: off-line equalization time threshold + preset time.
Optionally, in one embodiment of the present application, the vehicle battery pack includes: and (5) a lithium iron phosphate battery pack.
An embodiment of a third aspect of the present application provides a vehicle including: the method comprises the steps of a memory, a processor and a vehicle battery pack power balancing program stored in the memory and capable of running on the processor, wherein the vehicle battery pack power balancing program is executed by the processor to realize the power balancing method of the vehicle battery pack according to the embodiment.
An embodiment of a fourth aspect of the present application provides a computer-readable storage medium storing a power equalization program of a vehicle battery pack, which when executed by a processor, implements the steps of the power equalization method of the vehicle battery pack described in the above embodiment.
The application has the beneficial effects that:
(1) The application increases the equalization conditions, increases the equalization opportunity through the multipoint equalization triggering conditions, and indicates that the vehicle meets the equalization conditions for triggering the equalization when any one of the equalization conditions is met, thereby increasing the conditions for triggering the equalization of the battery and further increasing the equalization opportunity of the battery pack of the vehicle.
(2) According to the application, the equalization time and the equalization required electric quantity are accurately calculated according to the data of the battery voltage, the battery electric quantity and the battery current, so that the calculated corresponding equalization time and equalization required electric quantity can be conveniently used in discharge equalization or electricity compensation equalization, and the equalization mode is intelligently selected according to the use scene and the use habit of a user, thereby being beneficial to improving the equalization safety of the vehicle battery pack.
(3) According to the application, the electricity compensation equalization or the discharge equalization is selected according to the comparison condition of the low-voltage core number and the preset core number, the storage battery with preset voltage is selected to carry out the electricity compensation on the low-voltage core through the high-low-voltage direct-current converter until the equalization reaches the target electric quantity, the equalization load is reduced, the equalization efficiency is improved, the load of a resistance energy consumption equalization system is reduced, or the discharge point equalization is selected, namely, the electric quantity of the high-electric-quantity core is reduced to the target electric quantity by adopting a resistance electricity consumption mode, the electricity consumption is carried out on the high-electric-quantity core, and the equalization current is small.
(4) When the electric quantity of the storage battery is lower than a certain SOC, the vehicle is controlled to carry out reverse electricity supplementing, namely, the storage battery is supplemented by the vehicle battery pack, after the electricity supplementing of the storage battery is completed, if the balance condition is met, the balanced electricity supplementing is continued, or the electricity supplementing can not be carried out or stopped when the electric quantity of the storage battery reaches the target electric quantity, so that the balanced operation of the vehicle battery pack can be avoided when the electric quantity of the storage battery is too low.
(5) When the vehicle is detected to meet one of a plurality of equalization conditions, the application collects the related battery data of the vehicle battery pack, so as to calculate equalization time and equalization required electric quantity, then intelligently selects an equalization mode according to different use scenes and use habits of users, calculates the equalization time as accurately as possible, avoids error equalization, and finally selects power compensation equalization or discharge equalization according to the comparison condition of the number of low-voltage cores and the number of preset electric cores, wherein the power compensation equalization is to select a storage battery with preset voltage to supplement power to the low-voltage cores until the equalization reaches the target electric quantity, reduce the equalization load, improve the equalization efficiency, reduce the load of a resistance energy consumption equalization system, and the discharge equalization is to reduce the electric quantity of the high-power core to the target electric quantity by adopting the resistance power consumption mode, so as to consume electricity to the high-power core with small equalization current; the safety and the service life of the vehicle battery pack are improved.
Additional aspects and advantages of the application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the application.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a preferred embodiment of a method for balancing the charge of a vehicle battery pack according to the present application;
FIG. 2 is a schematic diagram of the OCV-SOC curve of a lithium iron phosphate cell in a preferred embodiment of the method for balancing the charge of a vehicle battery pack according to the present application;
FIG. 3 is a schematic diagram of a dQ/dV-SOC curve of a constant current charge of a lithium iron phosphate battery in a preferred embodiment of a method for balancing the charge of a vehicle battery pack of the present application;
FIG. 4 is a flow chart of an intelligent balancing strategy in a preferred embodiment of the method for balancing the power of a vehicle battery pack according to the present application;
FIG. 5 is a schematic diagram of an equalization circuit in a preferred embodiment of a method for equalizing the charge of a vehicle battery pack according to the present application;
FIG. 6 is a flowchart illustrating steps performed during the whole process of the method for balancing the electric power of the vehicle battery pack according to the preferred embodiment of the present application;
FIG. 7 is a schematic diagram of a preferred embodiment of a power balancing system for a vehicle battery pack according to the present application;
fig. 8 is a schematic structural view of a preferred embodiment of the vehicle of the present application.
Wherein, the 10-vehicle battery pack is an electric quantity balancing system; 100-data acquisition module, 200-balance calculation module and 300-balance control module; 501-memory, 502-processor and 503-communication interface.
Detailed Description
Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present application and should not be construed as limiting the application.
In the prior art, a passive equalization system of a lithium iron phosphate battery pack uses an accurate residual electric quantity SOC difference as an equalization basis, passive equalization action is carried out when a lithium iron phosphate battery pack is at a high-voltage end, screening of an equalization judgment basis is separated from execution of the equalization action, so that separation equalization judgment and execution timing are not necessarily carried out at the same time, a complete passive equalization scheme is provided, long-time equalization can be carried out after equalization is carried out, but battery cells needing equalization can be confirmed only in a part of SOC interval, and equalization capacity is determined; the battery pack used in the lithium iron phosphate battery platform area for a long time cannot accurately calculate the equalization time, and the trigger equalization opportunity is low; in addition, when equalization is executed, power consumption is carried out on the high-power battery cells, equalization current is small, energy is wasted, when only the voltage of each battery cell is low, the load of an equalization system is large, and the time required for equalization is long. In the prior art, a balance method is determined through a sub-scene, and the balance method comprises a driving balance method, a charging balance method, a short-time storage balance method and a long-time storage balance method, and the balance time is determined through the sub-scene, so that the balance time is more accurate. However, the essence of the method is that the equalization time is calculated through an OCV-SOC (open circuit voltage-state of charge) curve table, and in each equalization scene, if the battery pack SOC interval is in the lithium iron phosphate battery platform voltage section, the equalization time still cannot be accurately calculated; and when equalization is executed, the high-power battery cells consume electricity, the equalization current is small, when only the voltage of each battery cell is low, the load of the equalization system is large, the equalization time is long, and the energy is wasted.
The traditional lithium iron phosphate passive equalization needs to judge the standing time, the standing time is larger than 2h before and after restarting or the current is smaller than 0.03C (C represents the current multiplying power, such as 28Ah battery cell, 1C discharge is 28A,0.03C discharge is 0.03X 28A), the open circuit voltage of the battery cell can be read, and the equalization time can be calculated in a non-platform voltage area. Aiming at the voltage characteristics of the lithium iron phosphate battery pack and the lithium iron phosphate, the balance opportunities are small, so that the balance time is difficult to calculate accurately, and the error balance conditions are more; the disadvantage of long passive equalization time. The application aims to provide a multi-point triggering efficient intelligent balancing strategy applied to a lithium iron phosphate battery pack, solve the balancing problem of the lithium iron phosphate battery pack, and improve the performance and service life of the lithium iron phosphate battery pack.
The following describes a method and a system for balancing electric quantity of a vehicle battery pack and a vehicle according to embodiments of the present application with reference to the accompanying drawings. Aiming at the problems that the voltage characteristic of a vehicle battery pack (lithium iron phosphate) is low, the balancing time is difficult to calculate accurately, the error balancing condition is more, the passive balancing time is long, the service life and performance of the vehicle battery pack (lithium iron phosphate battery pack) are reduced, and even the vehicle battery pack is damaged or potential safety hazard is generated when the service life and performance are serious; the performance and the service life of the vehicle battery pack are improved. Therefore, the technical problems that in the related art, due to the voltage characteristics of the vehicle battery pack (lithium iron phosphate), the balancing opportunities are small, the balancing time is difficult to calculate accurately, the error balancing condition is more, the passive balancing time is long, the service life and performance of the vehicle battery pack (lithium iron phosphate battery pack) are reduced, and even the vehicle battery pack is damaged or potential safety hazards are generated when serious are solved.
In the application, if the vehicle is in a power-on state and the vehicle meets an equalization condition for triggering equalization, battery data of a vehicle battery pack are collected; calculating to obtain equalization time and equalization required electric quantity according to the battery data, and selecting an equalization mode according to a use scene and a use habit; and if the low-voltage core number is larger than the preset core number, reducing the electric quantity of the high-electric-quantity electric core to the target electric quantity by adopting a resistance power consumption mode, and improving the performance and the service life of the vehicle battery pack.
Specifically, fig. 1 is a flow chart of a method for balancing electric quantity of a vehicle battery pack according to an embodiment of the present application.
As shown in fig. 1, the method for equalizing the electric quantity of the vehicle battery pack includes the steps of:
in step S1, if the vehicle is in a power-on state and the vehicle satisfies an equalization condition that triggers equalization, battery data of a vehicle battery pack is collected.
It can be understood that the vehicle battery pack in the embodiment of the present application includes a lithium iron phosphate battery pack, and the multi-point triggering efficient intelligent equalization of the present application is mainly directed to the lithium iron phosphate battery pack, and fig. 2 shows an OCV-SOC curve of a lithium iron phosphate battery cell, as shown in fig. 2, it can be seen that in a 30-95% SOC interval, the OCV change is not obvious, and there is not enough slope to provide SOC correction and equalization time calculation, so that the present application can increase the SOC interval of the lithium iron phosphate for calculating the equalization time as much as possible.
Thus, the equalization conditions in the embodiments of the present application include (i.e., equalization on conditions): the lowest SOC of the battery cell is larger than a first percentage (for example, the first percentage is preferably 10%), the difference between the highest SOC and the lowest SOC of the battery cell is larger than a second percentage (for example, the second percentage is preferably 2%), the maximum voltage difference of the battery cell is larger than a preset voltage value (for example, the preset voltage value is preferably 10 mV), the residual balancing time is larger than 0, the whole vehicle has no faults, the temperature of a balancing circuit is smaller than a first temperature (for example, the first temperature is preferably 80 ℃) and the temperature of the battery cell is smaller than a second temperature (for example, the second temperature is preferably 55 ℃), and the electric quantity of a storage battery during power compensation balancing is larger than a third percentage SOC (for example, the third percentage is preferably 30%); and when any one of the equalization conditions is met, the vehicle is indicated to meet the equalization condition for triggering equalization.
The embodiment of the application sets a plurality of equalization conditions to increase the equalization opportunity through the multipoint equalization triggering conditions, wherein the equalization conditions relate to the lowest SOC of a battery cell, the difference between the highest SOC and the lowest SOC of the battery cell, the maximum voltage difference of the battery cell, the residual equalization time, the whole vehicle fault-free state, the temperature of an equalization circuit, the temperature of the battery cell and the electric quantity of a storage battery during the power-up equalization, and the equalization conditions indicate that the vehicle meets the equalization triggering conditions when any one of the equalization conditions is met, and the equalization conditions for triggering the battery equalization are increased, so that the equalization opportunity of a battery pack of the vehicle is increased. The application increases the equalization opportunity through the multipoint triggering condition. Besides the traditional screening and balancing time calculation of the static balancing object in the 10% -30% SOC interval, the screening and balancing time calculation of the static balancing object in the low SOC interval (for example, 3% -10%), the screening and balancing time calculation of the constant current charging balancing object in the 50% SOC and below, the AC full charge balancing and the large differential pressure balancing screening are added.
The battery data in the embodiment of the application comprises battery voltage, battery electric quantity and battery current, and the embodiment of the application can collect the data such as the battery voltage, the battery electric quantity and the battery current of the battery pack of the vehicle after the vehicle is in a power-on state and the vehicle meets the equalization condition for triggering equalization, thereby being convenient for accurately calculating and obtaining equalization time and equalization required electric quantity according to the data such as the battery voltage, the battery electric quantity and the battery current.
In step S2, an equalization time and an amount of electricity required for equalization are calculated according to the battery data, and an equalization mode is selected according to a usage scenario and usage habits.
It may be appreciated that the equalization time in the embodiment of the present application includes: the equalization time of passive resistor and the equalization time of battery power supply; passive resistance equalization time = Δe/(I) 2 * R), wherein delta E is balanced electric quantity, I is balanced current, and R is balanced resistor; battery charge equalization time = Δe/(p×η), where Δe is the equalization power, P is the battery equalization power, and η is the loss factor. In the embodiment of the application, the passive resistance balancing is balancing through resistance power consumption, the battery power compensation balancing is balancing through battery (the application preferably adopts a 12V battery), the passive resistance balancing time is calculated according to balancing electric quantity, balancing current and balancing resistance, and the battery power compensation balancing time is calculated according to balancing electric quantity and battery balancing power The rate and the loss factor are calculated, so that the calculated corresponding equalization time can be conveniently used later in discharge equalization or power-up equalization, the equalization time can be calculated as accurately as possible, and error equalization is avoided.
FIG. 3 shows a dQ/dV-SOC curve of the constant current charge of the lithium iron phosphate battery, as shown in FIG. 3, the dQ/dV can accurately correspond to the SOC under 50% of the SOC in the constant current charge, if the state of the constant current charge is in a direct current charging state, the direct current charge is a constant current step charging method, and the electric quantity to be balanced can be accurately calculated through the dQ/dV-SOC curve of the constant current charge of the lithium iron phosphate battery under 50% of the SOC.
Further, as shown in fig. 4, acquiring a voltage difference of the battery cell, and judging whether the voltage difference of the battery cell is larger than a voltage difference threshold value or not; if the voltage difference of the battery cells is larger than the voltage difference threshold, judging whether the standing time of the whole vehicle is longer than a preset time (for example, the preset time is preferably 2 h) and judging whether the SOC interval is in a preset range SOC interval (for example, the preset range SOC interval is preferably 10% -30%); if the standing time of the whole vehicle is longer than the preset time (2 h) and the SOC interval is in the preset range SOC interval (10% -30%), an OCV-SOC table lookup method is selected to calculate the electric quantity required by equalization; if the standing time of the whole vehicle is not longer than the preset time (2 h) or the SOC interval is not in the preset range SOC interval (10% -30%), judging whether the vehicle is in a direct current charging state; if the vehicle is in a direct-current charging state, calculating the electric quantity required by equalization through a dQ/dV-SOC curve (shown in figure 3) of constant-current charging of the lithium iron phosphate battery; if the vehicle is not in the direct-current charging state, judging whether the vehicle is in the alternating-current charging state; if the vehicle is in an ac charge state, the battery cells are screened at the end of charge to calculate the amount of charge needed for equalization greater than a fourth percentage (e.g., the fourth percentage is preferably 97%) SOC.
The embodiment of the application can select the mode for calculating the electric quantity required by equalization according to the judgment of the voltage difference of the battery cell, the standing time of the whole vehicle, the SOC interval, the direct current state of charge and the alternating current state of charge, and comprises three modes for calculating the electric quantity required by equalization, namely an OCV-SOC table look-up method, a constant-current charging dQ/dV-SOC curve of a vehicle battery pack and calculation of the charging end, so that the electric quantity required by equalization can be accurately calculated, and the calculated electric quantity required by equalization can be conveniently used in the subsequent discharge equalization or the electricity compensation equalization.
Further, as shown in fig. 4, the balancing scene is mainly performed in three ways, and whether the whole vehicle is electrified is judged; if the whole vehicle is not electrified, adopting off-line equalization during parking; if the whole vehicle is electrified, judging whether the vehicle speed is 0; if the vehicle speed is 0, adopting static balancing; if the vehicle speed is not 0, driving equalization is adopted. The embodiment of the application can intelligently select the balancing modes according to the use scene and the use habit of the user, wherein the balancing modes comprise off-line parking balancing, standing balancing and driving balancing, so that the most suitable balancing mode can be selected according to different conditions, and the balancing safety of the vehicle battery pack is improved.
In step S3, the low-voltage core number is obtained, if the low-voltage core number is smaller than or equal to the preset core number, a storage battery with preset voltage is selected to supplement power to the low-voltage core until the balance reaches the target electric quantity, and if the low-voltage core number is larger than the preset core number, the electric quantity of the high-electric-quantity core is reduced to the target electric quantity by adopting a resistance power consumption mode.
As can be understood, as shown in fig. 4, in the present application, the preset number of electric cores=a×total number of electric cores (electric cores with different electric quantities are different), the number of low-voltage electric cores is obtained, and whether the number of low-voltage electric cores is less than or equal to a×total number of electric cores is determined, where a is a constant less than 0.5; if the number of the low-voltage electric cores is smaller than or equal to the total number of the electric cores A, selecting a storage battery with preset voltage (12V) to supplement electricity to the low-voltage electric cores through a high-low voltage direct current converter (DC-DC) until the balance reaches the target electric quantity; and if the low-voltage core number is larger than the total number of the battery cores A, reducing the electric quantity of the battery core with high electric quantity to the target electric quantity by adopting a resistance power consumption mode.
According to the embodiment of the application, the charge balance or discharge balance can be selected according to the comparison condition of the low-voltage core number and the preset core number, if the low-voltage core number is smaller than or equal to the total number of the A-type electric cores, the charge balance is selected, namely, a storage battery with preset voltage is selected to charge the low-voltage core through a high-low-voltage direct-current converter until the balance reaches the target electric quantity, the balance load is reduced, the balance efficiency is improved, the load of a resistance energy consumption balance system is reduced, if the low-voltage core number is larger than the total number of the A-type electric cores, the discharge balance is selected, namely, the electric quantity of the high-power core is reduced to the target electric quantity by adopting a resistance power consumption mode, the electric power consumption is carried out on the high-power core, and the balance current is small.
Specifically, as shown in fig. 4, the flow of the intelligent equalization strategy of the present application is as follows:
starting;
step S10, acquiring a cell voltage difference, and judging whether the cell voltage difference is larger than a voltage difference threshold value or not; if the voltage difference of the battery cells is larger than the voltage difference threshold value, executing step S11;
step S11, judging whether the standing time of the whole vehicle is longer than 2 hours and judging whether the SOC interval is in a non-platform section (namely, whether the SOC interval is in 10% -30%); if the whole vehicle is kept still for longer than 2 hours and the SOC interval is in a non-platform section, executing a step S12;
if the whole vehicle standing time is not longer than 2h or the SOC interval is not in the non-platform section, executing the step S13;
step S12, if the whole vehicle is kept still for longer than 2 hours and the SOC interval is in a non-platform section, selecting an OCV-SOC table lookup method to calculate the electric quantity required by equalization;
step S13, judging whether the vehicle is in a direct current charging state or not; if the vehicle is in a DC charge state, executing step S14;
if the vehicle is not in the DC charge state, executing step S15;
step S14, if the vehicle is in a direct current charging state, calculating the electric quantity required by equalization through a dQ/dV-SOC curve of constant current charging of the lithium iron phosphate battery;
step S15, if the vehicle is not in the direct-current charging state, judging whether the vehicle is in the alternating-current charging state; if the vehicle is in an ac charge state, step S16 is performed;
Step S16, if the vehicle is in an alternating-current charging state, screening the battery cells at the charging end, and calculating the electric quantity required by equalization when the SOC is more than 97%;
step S17, judging whether the whole vehicle is electrified; if the whole vehicle is not electrified, executing a step S18;
if the whole vehicle is electrified, executing a step S19;
step S18, if the whole vehicle is not electrified, adopting off-line equalization during parking;
step S19, judging whether the vehicle speed is 0; if the vehicle speed is 0, executing step S20;
if the vehicle speed is not 0, executing step S21;
step S20, if the vehicle speed is 0, adopting static balancing;
step S21, if the vehicle speed is not 0, adopting driving equalization;
step S22, obtaining the number of low-voltage cores, and judging whether the number of the low-voltage cores is smaller than or equal to the total number of the A-type electric cores; if the low-voltage core number is greater than the total number of the battery cores a, executing step S23;
if the low-voltage core number is less than or equal to the total number of the battery cores A, executing a step S24;
step S23, if the low-voltage core number is larger than the total number of the battery cores A, adopting a resistance power consumption mode (discharge balance) to reduce the electric quantity of the high-electric-quantity battery core to the target electric quantity;
step S24, if the number of the low-voltage electric cores is smaller than or equal to the total number of the electric cores A, selecting a storage battery with preset voltage (12V), and supplementing electricity (balancing electricity) to the electric cores through a high-low voltage direct current converter (DC-DC) until the balancing reaches the target electric quantity;
Step S25, judging whether the equalization reaches the target electric quantity or does not meet the equalization condition; if the equalization reaches the target electric quantity or the equalization condition is not met, ending;
if the equalization does not reach the target electric quantity or the equalization condition is met, returning to execute the step S23 or the step S24;
and (5) ending.
Further, when the battery cell is charged by the battery with the preset voltage (12V), if the electric quantity of the battery is lower than the SOC of the fifth percentage (for example, the fifth percentage is preferably 30%), the battery is out of balance, the vehicle battery pack charges the battery (i.e., reversely charges), if the balance condition is met, the battery is controlled to perform balanced charging, and if the charging reaches the target electric quantity or the charging condition is not met, the charging is stopped. According to the embodiment of the application, when the electric quantity of the storage battery is lower than a certain SOC, the vehicle can be controlled to carry out reverse electricity supplementing, namely, the storage battery is supplemented by the vehicle battery pack, after the electricity supplementing of the storage battery is completed, if the balance condition is met, the balanced electricity supplementing is continued, or the electricity supplementing can not be carried out or stopped when the electricity supplementing reaches the target electric quantity, so that the balanced operation of the vehicle battery pack can be avoided when the electric quantity of the storage battery is too low.
According to the application, a 12V storage battery is adopted to supplement electricity for a low-voltage battery core, so that the balance load is reduced, and the balance efficiency is improved; when part of the cell voltage is lower than the average voltage and the equilibrium pressure difference standard is reached, the cell can be reversely supplied with electricity through a DC-DC module of the vehicle-mounted OBC by a 12V low-voltage power supply (storage battery), the electricity supplying current is larger, and the equilibrium efficiency is high; when the electric quantity of the 12V low-voltage power supply (storage battery) is low, equalization is stopped, and the battery pack supplements power for the 12V low-voltage power supply (storage battery); the balance efficiency can be improved, and the load of the resistance energy consumption balance system can be reduced.
Further, fig. 5 is a schematic diagram of an equalization circuit according to the present application, where in the equalization system according to the embodiment of the present application, the equalization system may perform energy consumption equalization on a cell with too high energy through a resistor, or may perform power supply on a cell with a low cell voltage through DC-DC by using a 12V storage battery. And acquiring the single-cell voltage of the current core in real time, judging whether an equalization condition is reached according to the acquired data and the state of the whole vehicle, and selecting a proper equalization strategy according to the state of the whole vehicle and the battery. For example, when it is determined that the voltage of the single cell C1 in fig. 5 is too high, the balanced discharge condition is satisfied, and the control circuit opens the corresponding discharge circuit to perform the discharge through the balanced resistor (R1 in fig. 5). When the discharge reaches the target value (or reaches the equilibrium limiting condition), the discharge equilibrium is automatically stopped. When the voltage of the single battery cell C1 in the graph 5 is judged to be too low, the balanced electricity supplementing condition is met, electricity supplementing is needed, the control circuit opens a corresponding electricity supplementing loop, and electricity supplementing is carried out through the 12V storage battery. When the electric quantity of the 12V storage battery is lower than 30% SOC, the vehicle battery pack (large battery pack) supplements power for the 12V storage battery through DC-DC, and after the 12V storage battery is supplemented, balanced power supplement is continued. And when the power is supplied to the target value or the power supply condition is not met, the power supply is automatically stopped. And by combining the power supply equalization and the resistance discharge equalization, the equalization efficiency is improved, and the load of an equalization system is reduced.
The overall implementation is further described in terms of steps for performing the method for balancing the charge of a vehicle battery pack according to the present application, as shown in fig. 6:
starting;
step S100, judging whether the vehicle is in a power-on state; if the vehicle is in a powered-on state, step S101 is executed;
if the vehicle is not in the powered-on state, step S112 is performed;
step S101, if the vehicle is in a power-on state, judging whether the vehicle meets an equilibrium condition; if the vehicle satisfies the equalization condition, step S103 is performed;
if the vehicle does not meet the equalization condition, step S102 is executed;
step S102, if the vehicle does not meet the balance condition, the vehicle exits the balance;
step S103, if the vehicle meets the balance condition, reading the historical residual balance time and balance mode;
step S104, selecting an equalization mode according to the current state of the vehicle, calculating equalization time, comparing the equalization time with historical equalization information, and selecting an optimal equalization strategy;
step S105, judging whether the equalization time is more than 0; if the equalization time is equal to 0, step S106 is performed;
if the equalization time is greater than 0, step S107 is performed;
step S106, if the equalization time is equal to 0, the equalization is exited;
step S107, if the equalization time is greater than 0, the equalization time is stored in real time, the equalization time is subjected to the number reduction treatment, after a certain equalization time (different equalization systems and battery packs are not necessarily needed), the equalization condition judgment is carried out, and the balanced time is subtracted from the equalization time to obtain the residual equalization time;
Step S108, judging whether a fault or a limiting condition affecting balance exists; if there is a fault or a constraint affecting equalization, step S109 is performed;
if there is no fault or constraint affecting equalization, step S110 is performed;
step S109, if a fault or a limiting condition affecting equalization exists, exiting equalization;
step S110, judging whether a power-down request is detected (a power-down request signal is generated by the whole vehicle controller) if no fault or limiting condition affecting balance exists; if no power-down request is detected, step S105 is performed (i.e., whether the equalization time is greater than 0 is continuously determined);
if a power-down request is detected, step S111 is performed;
step S111, if a power-down request is detected, storing balance residual duration and balance parameters and powering down;
step S112, judging whether the BMS system meets the timed wake-up or the offline balancing condition if the vehicle is not in the power-on state; if the BMS system does not meet the timed wake-up or the offline balancing condition, executing step S113;
if the BMS system meets the timed wake-up or the offline balance bar, executing step S114;
step S113, if the BMS system does not meet the timed wake-up (the BMS system is not started after long-time parking, the whole vehicle can wake up the BMS system at a certain time interval) or the offline equalization condition is not met, the offline equalization is not performed;
Step S114, if the BMS system meets the timing wake-up or the offline balancing condition, the historical residual balancing time and balancing mode are read;
step S115, judging whether the residual equalization time is greater than an offline equalization time threshold t; if the remaining equalization time is greater than the offline equalization time threshold t, step S116 is performed;
if the remaining equalization time is not greater than the offline equalization time threshold t, step S117 is performed;
step S116, if the remaining balancing time is greater than the offline balancing time threshold, setting the offline balancing time as the offline balancing time threshold (t), and performing offline balancing;
step S117, setting the BMS wake-up time to: an offline equalization time threshold value is +2h (the battery is kept still for longer than 2h to obtain accurate open-circuit voltage OCV), and whether offline equalization judgment is carried out again;
and (5) ending.
In summary, the embodiment of the application can collect relevant battery data of a vehicle battery pack when the vehicle is detected to meet one of a plurality of equalization conditions, so as to calculate equalization time and equalization required electric quantity, intelligently select an equalization mode according to different use scenes and use habits of users, calculate the equalization time as accurately as possible, avoid error equalization, and finally select power-supplementing equalization or discharge equalization according to the comparison condition of the number of low-voltage cores and the number of preset electric cores, wherein the power-supplementing equalization is to select a storage battery with preset voltage to supplement power to the low-voltage cores until the equalization reaches the target electric quantity, reduce the equalization load, improve the equalization efficiency, reduce the load of a resistance energy consumption equalization system, reduce the electric quantity of the high-power-consumption electric core to the target electric quantity by adopting the resistance power consumption mode, consume electricity to the high-power-consumption electric core and realize small equalization current; the safety and the service life of the vehicle battery pack are improved.
Next, a power equalization system of a vehicle battery pack according to an embodiment of the present application will be described with reference to the accompanying drawings.
Fig. 7 is a block diagram of a charge equalization system for a vehicle battery pack according to an embodiment of the present application.
As shown in fig. 7, the charge equalization system 10 of the vehicle battery pack includes: the system comprises a data acquisition module 100, an equalization calculation module 200 and an equalization control module 300.
Specifically, the data collection module 100 is configured to collect battery data of a vehicle battery pack if the vehicle is in a power-on state and the vehicle meets an equalization condition for triggering equalization.
And the equalization calculation module 200 is used for calculating equalization time and equalization required electric quantity according to the battery data, and selecting an equalization mode according to a use scene and a use habit.
The balancing control module 300 is configured to obtain a low-voltage core count, if the low-voltage core count is less than or equal to a preset core count, select a storage battery with a preset voltage to supplement power to the low-voltage core until balancing reaches a target power, and if the low-voltage core count is greater than the preset core count, reduce the power of the high-power core to the target power by adopting a resistance power consumption mode.
Optionally, in one embodiment of the present application, the equalization condition includes: the lowest SOC of the battery cell is larger than the first percentage, the difference between the highest SOC and the lowest SOC of the battery cell is larger than the second percentage, the maximum voltage difference of the battery cell is larger than a preset voltage value, the residual balancing time is larger than 0, the whole vehicle has no faults, the temperature of a balancing circuit is smaller than the first temperature and the temperature of the battery cell is smaller than the second temperature, and the electric quantity of a storage battery during power compensation balancing is larger than the third percentage SOC; and when any one of the equalization conditions is met, the vehicle is indicated to meet the equalization condition for triggering equalization.
Optionally, in one embodiment of the application, the battery data includes a battery voltage, a battery charge, and a battery current.
Optionally, in one embodiment of the present application, the equalizing time includes: the equalization time of passive resistor and the equalization time of battery power supply; passive resistance equalization time = Δe/(I) 2 * R), wherein delta E is balanced electric quantity, I is balanced current, and R is balanced resistor; battery charge equalization time = Δe/(p×η), where Δe is the equalization power, P is the battery equalization power, and η is the loss factor.
Optionally, in one embodiment of the present application, the equalization calculation module 200 includes: the battery cell differential pressure acquisition and comparison unit, the standing time length and SOC interval judgment unit, the first equalization required electric quantity calculation unit, the direct current charging state judgment unit, the second equalization required electric quantity calculation unit, the alternating current charging state judgment unit and the third equalization required electric quantity calculation unit.
The battery cell differential pressure acquisition and comparison unit is used for acquiring the battery cell differential pressure and judging whether the battery cell differential pressure is larger than a differential pressure threshold value or not.
And the static time length and SOC interval judging unit is used for judging whether the static time length of the whole vehicle is longer than the preset time and judging whether the SOC interval is in the preset range or not if the voltage difference of the battery cell is greater than the voltage difference threshold value.
And the first equalization required electric quantity calculation unit is used for selecting an OCV-SOC table look-up method to calculate equalization required electric quantity if the whole vehicle is longer than the preset time and the SOC interval is in the preset range SOC interval when standing.
And the direct current charging state judging unit is used for judging whether the vehicle is in a direct current charging state or not if the standing time of the whole vehicle is not longer than the preset time or the SOC interval is not in the preset range SOC interval.
And the second equalization required electric quantity calculation unit is used for calculating the equalization required electric quantity through a vehicle battery pack constant-current charging dQ/dV-SOC curve if the vehicle is in a direct-current charging state.
And the alternating current charging state judging unit is used for judging whether the vehicle is in the alternating current charging state or not if the vehicle is not in the direct current charging state.
And the third equalization required electric quantity calculation unit is used for screening the battery cells at the charging end if the vehicle is in an alternating-current charging state, and calculating the equalization required electric quantity larger than the fourth percentage SOC.
Optionally, in one embodiment of the present application, the equalization calculation module 200 further includes: the vehicle speed control system comprises a first whole vehicle power-on judging unit, a first balancing mode selecting unit, a vehicle speed judging unit, a second balancing mode selecting unit and a third balancing mode selecting unit.
The first whole vehicle power-on judging unit is used for judging whether the whole vehicle is powered on or not.
The first equalization mode selection unit is used for adopting off-line equalization when the whole vehicle is not electrified.
And the vehicle speed judging unit is used for judging whether the vehicle speed is 0 or not if the whole vehicle is electrified.
And the second equalization mode selecting unit is used for adopting static equalization if the vehicle speed is 0.
And the third equalization mode selecting unit is used for adopting driving equalization if the vehicle speed is not 0.
Optionally, in one embodiment of the present application, the equalization control module 300 includes: the device comprises a low-voltage core number acquisition comparison unit, a power compensation equalization unit and a discharge equalization unit.
The low-voltage core number acquisition and comparison unit is used for acquiring the low-voltage core number and judging whether the low-voltage core number is smaller than or equal to the total number of the electric cores A, wherein A is a constant smaller than 0.5.
And the electricity supplementing and balancing unit is used for selecting a storage battery with preset voltage to supplement electricity to the low-voltage electric core through the high-low voltage direct current converter if the number of the low-voltage electric cores is smaller than or equal to the total number of the electric cores A until balancing reaches the target electric quantity.
And the discharging equalization unit is used for reducing the electric quantity of the high-electric-quantity electric core to the target electric quantity by adopting a resistance power consumption mode if the low-voltage electric core number is larger than the total number of the electric cores A.
Optionally, in one embodiment of the present application, the power equalization system 10 of the vehicle battery pack of the embodiment of the present application further includes: the system comprises a reverse power-up unit, an equalization time judging unit, an equalization time processing unit, a fault or limiting condition judging unit, a power-down request judging unit, a storage power-down unit, a BMS system judging unit, an equalization time and equalization mode reading unit, a historical remaining equalization time judging unit, an offline equalization unit, a first wake-up time setting unit and a second wake-up time setting unit.
The reverse electricity supplementing unit is used for supplementing electricity to the battery core through the storage battery with preset voltage, if the electric quantity of the storage battery is lower than a fifth percentage SOC, the storage battery is out of balance, the vehicle battery pack supplements electricity to the storage battery, if the balance condition is met, the storage battery is controlled to supplement electricity in balance, and if the electricity supplementing reaches the target electric quantity or does not meet the electricity supplementing condition, the electricity supplementing is stopped.
And the equalization time judging unit is used for judging whether the equalization time is greater than 0.
And the equalization time processing unit is used for storing the equalization time in real time and performing reduction processing on the equalization time if the equalization time is greater than 0.
And the fault or limiting condition judging unit is used for judging whether a fault or limiting condition affecting balance exists.
And the power-down request judging unit is used for judging whether the power-down request is detected if no fault or limiting condition affecting balance exists.
And the power-down storage unit is used for storing the balance residual duration and the balance parameters and powering down the battery if the power-down request is detected.
And the BMS system judging unit is used for judging whether the BMS system meets the timed wake-up or whether the BMS system meets the offline balancing condition if the vehicle is not in the power-on state.
And the balancing time and balancing mode reading unit is used for reading the historical residual balancing time and balancing mode if the BMS system meets the timing wake-up or the offline balancing condition.
And the historical residual equalization time judging unit is used for judging whether the historical residual equalization time is larger than an offline equalization time threshold.
And the offline balancing unit is used for setting the offline balancing time as the offline balancing time threshold and performing offline balancing after the offline balancing time is set as the offline balancing time threshold if the historical remaining balancing time is greater than the offline balancing time threshold.
The first wake-up time setting unit is configured to set a BMS wake-up time to: off-line equalization time threshold + preset time.
The second wake-up time setting unit is configured to directly set the BMS wake-up time to be: off-line equalization time threshold + preset time.
Optionally, in one embodiment of the present application, the vehicle battery pack includes: and (5) a lithium iron phosphate battery pack.
It should be noted that the foregoing explanation of the embodiment of the method for balancing the electric quantity of the vehicle battery pack is also applicable to the electric quantity balancing system of the vehicle battery pack of this embodiment, and will not be repeated here.
According to the electric quantity balancing system of the vehicle battery pack, when the fact that a vehicle meets one of a plurality of balancing conditions is detected, relevant battery data of the vehicle battery pack are collected, so that balanced balancing time and balanced required electric quantity are calculated, then a balancing mode is intelligently selected according to different use scenes and use habits of users, balancing time is calculated as accurately as possible, error balancing is avoided, and finally electric compensation balancing or discharge balancing is selected according to the comparison condition of the number of low-voltage electric cores and the number of preset electric cores, wherein the electric compensation balancing is to select a storage battery with preset voltage to compensate electricity for a low-voltage electric core until balancing reaches the target electric quantity, balancing load is reduced, balancing efficiency is improved, resistance energy consumption balancing system load is reduced, the electric quantity of a high-electric-quantity electric core is reduced to the target electric quantity by adopting the resistance power consumption mode, electricity consumption is carried out on the high-electric-quantity electric core, and balancing current is small; the safety and the service life of the vehicle battery pack are improved.
Therefore, the technical problems that in the related art, due to the voltage characteristics of the vehicle battery pack (lithium iron phosphate), the balancing opportunities are small, the balancing time is difficult to calculate accurately, the error balancing condition is more, the passive balancing time is long, the service life and performance of the vehicle battery pack (lithium iron phosphate battery pack) are reduced, and even the vehicle battery pack is damaged or potential safety hazards are generated when serious are solved.
Fig. 8 is a schematic structural diagram of a vehicle according to an embodiment of the present application. The vehicle may include:
memory 501, processor 502, and a computer program stored on memory 501 and executable on processor 502.
The processor 502 implements the method for equalizing the electric power of the vehicle battery pack provided in the above-described embodiment when executing the program.
Further, the vehicle further includes:
a communication interface 503 for communication between the memory 501 and the processor 502.
Memory 501 for storing a computer program executable on processor 502.
The memory 501 may include high-speed RAM memory and may also include non-volatile memory (non-volatile memory), such as at least one disk memory.
If the memory 501, the processor 502, and the communication interface 503 are implemented independently, the communication interface 503, the memory 501, and the processor 502 may be connected to each other via a bus and perform communication with each other. The bus may be an industry standard architecture (Industry Standard Architecture, abbreviated ISA) bus, a Peripheral Component Interconnect (PCI) bus, an extended industry standard architecture (Extended Industry StandardArchitecture, abbreviated EIS) bus, or the like. The buses may be divided into address buses, data buses, control buses, etc. For ease of illustration, only one thick line is shown in fig. 8, but not only one bus or one type of bus.
Alternatively, in a specific implementation, if the memory 501, the processor 502, and the communication interface 503 are integrated on a chip, the memory 501, the processor 502, and the communication interface 503 may perform communication with each other through internal interfaces.
The processor 502 may be a central processing unit (Central Processing Unit, abbreviated as CPU) or an application specific integrated circuit (Application Specific Integrated Circuit, abbreviated as ASIC) or one or more integrated circuits configured to implement embodiments of the present application.
The present embodiment also provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method of equalizing the charge of a vehicle battery pack as above.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or N embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, "N" means at least two, for example, two, three, etc., unless specifically defined otherwise.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and additional implementations are included within the scope of the preferred embodiment of the present application in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order from that shown or discussed, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the embodiments of the present application.
Logic and/or steps represented in the flowcharts or otherwise described herein, e.g., a ordered listing of executable instructions for implementing logical functions, can be embodied in any computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable storage medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: an electrical connection (electronic device) having one or N wires, a portable computer cartridge (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable storage medium may even be paper or other suitable medium upon which the program is printed, as the program may be electronically captured, via optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It is to be understood that portions of the present application may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the N steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. As with the other embodiments, if implemented in hardware, may be implemented using any one or combination of the following techniques, as is well known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like.
Those of ordinary skill in the art will appreciate that all or a portion of the steps carried out in the method of the above-described embodiments may be implemented by a program to instruct related hardware, where the program may be stored in a computer readable storage medium, and where the program, when executed, includes one or a combination of the steps of the method embodiments.
In addition, each functional unit in the embodiments of the present application may be integrated in one processing module, or each unit may exist alone physically, or two or more units may be integrated in one module. The integrated modules may be implemented in hardware or in software functional modules. The integrated modules may also be stored in a computer readable storage medium if implemented in the form of software functional modules and sold or used as a stand-alone product.
The above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, or the like. While embodiments of the present application have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the application, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the application.
It is to be understood that the application is not limited in its application to the examples described above, but is capable of modification and variation in light of the above teachings by those skilled in the art, and that all such modifications and variations are intended to be included within the scope of the appended claims.
Claims (15)
1. The electric quantity balancing method for the vehicle battery pack is characterized by comprising the following steps of:
if the vehicle is in a power-on state and the vehicle meets an equalization condition for triggering equalization, acquiring battery data of a vehicle battery pack;
calculating to obtain equalization time and equalization required electric quantity according to the battery data, and selecting an equalization mode according to a use scene and a use habit;
and obtaining the low-voltage core number, if the low-voltage core number is smaller than or equal to the preset core number, selecting a storage battery with preset voltage to supplement electricity for the low-voltage core until the balance reaches the target electric quantity, and if the low-voltage core number is larger than the preset core number, reducing the electric quantity of the high-electric-quantity core to the target electric quantity by adopting a resistance power consumption mode.
2. The method for equalizing the charge of a vehicle battery pack according to claim 1, wherein the equalization conditions include: the lowest SOC of the battery cell is larger than the first percentage, the difference between the highest SOC and the lowest SOC of the battery cell is larger than the second percentage, the maximum voltage difference of the battery cell is larger than a preset voltage value, the residual balancing time is larger than 0, the whole vehicle has no faults, the temperature of a balancing circuit is smaller than the first temperature and the temperature of the battery cell is smaller than the second temperature, and the electric quantity of a storage battery during power compensation balancing is larger than the third percentage SOC; and when any one of the equalization conditions is met, the vehicle is indicated to meet the equalization condition for triggering equalization.
3. The method of charge equalization of a vehicle battery pack of claim 1, wherein said battery data comprises battery voltage, battery charge, and battery current.
4. The method for equalizing the charge of a vehicle battery pack according to claim 1, wherein the equalizing time includes: the equalization time of passive resistor and the equalization time of battery power supply;
passive resistance equalization time = Δe/(I) 2 * R), wherein delta E is balanced electric quantity, I is balanced current, and R is balanced resistor;
battery charge equalization time = Δe/(p×η), where Δe is the equalization power, P is the battery equalization power, and η is the loss factor.
5. The method for equalizing the electric quantity of the vehicle battery pack according to claim 1, wherein the electric quantity required for equalization is calculated from the battery data, specifically comprising:
acquiring a cell voltage difference, and judging whether the cell voltage difference is larger than a voltage difference threshold value or not;
if the voltage difference of the battery cell is larger than the voltage difference threshold, judging whether the standing time of the whole vehicle is longer than the preset time and judging whether the SOC interval is in the preset range SOC interval;
if the standing time of the whole vehicle is longer than the preset time and the SOC interval is in the preset range SOC interval, selecting an OCV-SOC table lookup method to calculate the electric quantity required by equalization;
if the standing time of the whole vehicle is not longer than the preset time or the SOC interval is not in the preset range SOC interval, judging whether the vehicle is in a direct current charging state or not;
if the vehicle is in a direct current charging state, calculating the electric quantity required by equalization through a dQ/dV-SOC curve of constant current charging of a vehicle battery pack;
if the vehicle is not in the direct-current charging state, judging whether the vehicle is in the alternating-current charging state;
if the vehicle is in an alternating current charging state, the battery cells are screened at the charging end, and the electric quantity required by equalization is calculated and is larger than the fourth percentage of SOC.
6. The method for balancing the electric quantity of the vehicle battery pack according to claim 1, wherein the balancing mode is selected according to a use scenario and a use habit, and specifically comprises:
judging whether the whole vehicle is electrified;
if the whole vehicle is not electrified, adopting off-line equalization during parking;
if the whole vehicle is electrified, judging whether the vehicle speed is 0;
if the vehicle speed is 0, adopting static balancing;
if the vehicle speed is not 0, driving equalization is adopted.
7. The method for balancing the electric quantity of the vehicle battery pack according to claim 1, wherein the obtaining the low-voltage electric core number, if the low-voltage electric core number is smaller than or equal to a preset electric core number, selecting a storage battery with a preset voltage to supplement the electric quantity of the low-voltage electric core until the balancing reaches a target electric quantity, and if the low-voltage electric core number is larger than the preset electric core number, reducing the electric quantity of the high-electric-quantity electric core to the target electric quantity by adopting a resistance power consumption mode, specifically comprising:
obtaining the number of low-voltage cores, and judging whether the number of the low-voltage cores is smaller than or equal to the total number of the A-type electric cores, wherein A is a constant smaller than 0.5;
if the number of the low-voltage cores is smaller than or equal to the total number of the electric cores A, a storage battery with preset voltage is selected to supplement electricity to the low-voltage cores through a high-low voltage direct current converter until the balance reaches the target electric quantity;
And if the low-voltage core number is larger than the total number of the battery cores A, reducing the electric quantity of the battery core with high electric quantity to the target electric quantity by adopting a resistance power consumption mode.
8. The method for equalizing the charge of a vehicle battery pack according to claim 1 or 7, characterized in that the method for equalizing the charge of a vehicle battery pack further comprises:
when the battery cell is charged through the storage battery with preset voltage, if the electric quantity of the storage battery is lower than the fifth percentage SOC, the storage battery is out of balance, the vehicle battery pack supplements the electric quantity of the storage battery, if the balance condition is met, the storage battery is controlled to supplement the electric quantity in balance, and if the electric quantity of the storage battery reaches the target electric quantity or the electric quantity of the storage battery is not met, the electric quantity of the storage battery is stopped.
9. The method for balancing the electric quantity of the vehicle battery pack according to claim 1, wherein the obtaining the low-voltage electric core number, if the low-voltage electric core number is smaller than or equal to a preset electric core number, selecting a storage battery with a preset voltage to supplement the electric quantity of the low-voltage electric core until the balancing reaches a target electric quantity, if the low-voltage electric core number is larger than the preset electric core number, reducing the electric quantity of the high-electric-quantity electric core to the target electric quantity by adopting a resistance power consumption mode, and then further comprising:
Judging whether the equalization time is more than 0;
if the equalization time is greater than 0, preserving the equalization time in real time, and performing reduction processing on the equalization time;
judging whether a fault or a limiting condition affecting balance exists or not;
if no fault or limiting condition affecting balance exists, judging whether a power-down request is detected;
and if the power-down request is detected, storing the balance residual duration and the balance parameters, and powering down.
10. The method for equalizing a charge of a vehicle battery pack according to claim 1, wherein the method for equalizing a charge of a vehicle battery pack further comprises:
if the vehicle is not in the power-on state, judging whether the BMS system meets the timed wake-up or the offline equalization condition;
if the BMS system meets the timing wake-up or offline equalization conditions, reading historical residual equalization time and equalization modes;
judging whether the historical residual equalization time is larger than an offline equalization time threshold;
if the historical residual balancing time is greater than the offline balancing time threshold, setting the offline balancing time as the offline balancing time threshold, and performing offline balancing;
the BMS wake-up time is set to: off-line equalization time threshold + preset time.
11. The method for balancing the power of a vehicle battery pack according to claim 10, wherein the determining whether the historical remaining balancing time is greater than an offline balancing time threshold further comprises:
if the historical remaining equalization time is not greater than the offline equalization time threshold, the BMS wakeup time is directly set to: off-line equalization time threshold + preset time.
12. The method of charge equalization for a vehicle battery pack of claim 1, wherein said vehicle battery pack comprises: and (5) a lithium iron phosphate battery pack.
13. A charge equalization system for a vehicle battery pack, the charge equalization system for a vehicle battery pack comprising:
the data acquisition module is used for acquiring battery data of a vehicle battery pack if the vehicle is in a power-on state and the vehicle meets an equalization condition for triggering equalization;
the equalization calculation module is used for calculating equalization time and equalization required electric quantity according to the battery data, and selecting an equalization mode according to a use scene and a use habit;
the balance control module is used for obtaining the low-voltage core number, if the low-voltage core number is smaller than or equal to the preset core number, the storage battery with preset voltage is selected to supplement electricity for the low-voltage core until the balance reaches the target electric quantity, and if the low-voltage core number is larger than the preset core number, the electric quantity of the high-electric-quantity electric core is reduced to the target electric quantity in a resistance power consumption mode.
14. A vehicle, characterized in that the vehicle comprises: memory, a processor and a charge balancing program of a vehicle battery pack stored on the memory and operable on the processor, which when executed by the processor, implements the steps of the charge balancing method of a vehicle battery pack according to any one of claims 1-12.
15. A computer readable storage medium, characterized in that the computer readable storage medium stores a charge balancing program of a vehicle battery pack, which when executed by a processor, implements the steps of the charge balancing method of the vehicle battery pack according to any one of claims 1-12.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117549796A (en) * | 2023-12-27 | 2024-02-13 | 中航锂电（洛阳）有限公司 | Control method for passive equalization of battery and vehicle |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117549796A (en) * | 2023-12-27 | 2024-02-13 | 中航锂电（洛阳）有限公司 | Control method for passive equalization of battery and vehicle |
| CN117549796B (en) * | 2023-12-27 | 2024-06-18 | 中航锂电（洛阳）有限公司 | Control method for passive equalization of battery and vehicle |
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